Historically, there have been two main categories of American whiskey: bourbon and rye.
Both styles of whiskey have several things in common. One of the main similarities is that both must be aged in new, charred oak barrels, a major source of flavour and aroma in American whiskeys.
Historically associated with Kentucky, Bourbon is the more popular category. Despite popular belief, bourbon can be produced anywhere in the United States. Bourbon must be made with at least 51% corn, although it often contains substantially more. The remaining 49% can be comprised of a combination of other grains, typically malted barley and either rye or wheat. Bourbon is a good choice for those who are looking to start exploring whiskey, because its flavour profile tends to be sweet, leaning toward caramel, vanilla, soft spices, and wood.
Rye whiskey, bourbon’s northern counterpart has been making a comeback in recent years. Rye has to be made with at least 51% rye, with the remainder being up to the distiller, but usually consisting of malted barley and corn. Rye grain gives the whiskey a distinctive spice and fruit notes, making it more assertive than its mellow southern cousin
There are a number of other categories of American whiskies, such as Tennessee whiskey. Tennessee whiskey is essentially bourbon only it is made in Tennessee and then must be filleted through maple charcoal before aging. Corn whiskey must be made from at least 80% corn. Wheat whiskey, malt whiskey and rye malt whiskey must contain at least 51% of their namesake grain.